Aluminous compostion and method of making the same



UNITED STATES PATENT OFFICE.

OTIS HU'ICHINS, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO THE GABIBOBUNDUM COMPANY, OF NIAGARA. FALLS, NEW YORK, A CORPORATION OF PENNSYLVANIA.

ALUMINOUS COMPOSITION AND METHOD OF MAKING THE SAME.

1T0 Drawing.

concern To all whom it ma iiat I, OTIS Hu'rcmNs, a

Be it known t citizen of the United States, residing at.

following is a full, clear, and exact descrip-' tion.

This invention relates to an improved aluminous composition or abrasive and to the method of making the same. When abrasives are used 1n con unct1on with an adhesive, such as glue, for abrasive purposes, in the form of-an abrasive paper,

' cloth or bufiing wheel, the efliciency of the abrasive depends largely upon the amount of adhesionbetween the grain and the glue. The amount of adhesion-obtained is a function of the rouglmess 'of the surface of the abrasive. Artificial aluminous abrasives have normally 'a very smooth surface, and

consequently, when used in conjunction with glue, do not exhibit this property of adhesion to the extent of certain abrasives hav in rough surfaces, such as natural emery.

lractically all commercial aluminous abrasives have an alumina content of 92 to 98%, the remainder being oxids of titanium, silicon, iron, calcium and magnesium. The alumina for the most part appears in the form of alumina crystals, the other oxids present forming a glass. which acts as a matrix holding the alumina; crystals together. The size of these alumina crystals within the abrasive has an important bearing on the roughness of the surface of the abrasive grain. When these crystals are comparatively large, the surface of the abrasive grain will be comparatively smooth, as any surface area will consist of a fracture of one or at most of a very few alumina crystals. However. when the alumina crystals are comparatively small (very much smaller than the abrasive grains in mstion), the surface will be comparatively rough, as it will be composed of the sur faces of a' large number of small crystals-' not inthe same plane. A rough surfaceofthis character is well exemplified by natural emery where the alumina crystals are ex Specification of Letters Extent.

Patented May 4, 1920.

- Application filed September 18, 1919. Serial No. 324,553.

ceedingly minute; The average size of the" very smalland which, when crushed, furnishes abrasive grains having exceedingly rough surfaces can be produced by the introduction of strontium oxid into aluminous fusions such as are now used for the manufacture of abrasives. oxid apparently combines with some of the lmpunties present in the melt and or stal-. hzes in long needle-shaped crystals. ese long crystals are uniformly" distributed throughout the crystallized alumina, breakmg up 1nto a large number of small alumina crystals, acrystal growth which would otherwise have formed a large crystal.

The ultimate result is the formation of an abrasive in which the alumina: crystals are very small and'these crystals are, in turn, surrounded by others very much smaller which contain the strontium oxid.

In the preferred method of carrying out my invention, I have fused an.,electric furnace the following mixture:

300 parts aluminous waste, 170parts calcined bauxite, 30 parts strontium carbonate. 1 The aluminous waste analyzed as folows:

The strontium carbonate was the usual commercial grade.

The strontium may use carbon in the mixture fused to pro- The product from this fusion was dense,

of very rough fracture, and analyzed as fol-- lows:

SiO .24 'FeO .12 TiO 2. 68 S60 A1 0 92. 81

Tne materials were fused by the usual electric furnace process, such for example, as that described in the Tone patent, No. 1,002,608, of Septemberfi, 1911.

During the fusion, there was a certain amount of reduction of the iron-oxid, titanium oxid and silica, due to carbon from the duce a product of the desired purity.

I claim: r 1. A crystalline aluminous product containing strontium oxid, substantially as describe aluminous abrasive containing oxids of iron, silicon, titanium and stron-- tium, substantially as described...

' 3. An aluminous abrasive consisting of alumina crystals surrounded by smaller crystals which contain strontium oxid, sub- I stantially" as described.

4. An aluminous abrasive containing oxids of silicon, titanium and strontium, substantially as described.

5. The method of making an aluminous abrasive which consists in fusing in an electric furnace a mixture containing an aluminous material and a strontium compound which upon such furnace fusion yields strontium oxid, substantially as described. Y

6. The method of making an aluminous abrasive which consists in fusing in an electric furnace a mixture containing an aluminous material containing minor quantities of silicon, iron and titanium oxids, and a strontium compound which upon such furnace fusion yields strontium oxid, and supplying carbon in sufiicient quantity to reduce the major portionof the silicon, iron and titanium oxids, but insufficient to reduce the strontium oxid, substantially as described.

,7. The method of making an aluminous abrasive which consists in fusing a mixture containing an aluminous material and a strontium compound which leaves a strontium oxid in the product, substantially as described.

In testimony whereof I have hereunto set in hand.

y OTIS HUTCHINS. 

